Abstract
The need for an eco-friendly and sustainable source of energy has been the focus in recent years due to climate change caused by fossil fuels. The negative environmental impact of fossil fuels has led to the development of alternative energy sources. Microbial fuel cells (MFC) are an alternative source of energy that is eco-friendly and sustainable; it relies on the ability of microorganisms to produce electrons from oxidation of organic and inorganic molecules.
Over the years, various substrates, design, and materials have been used in order to improve power generation and reduces the cost in cell design and construction. This study was aimed at generating power from a low cost single chamber fuel cell, using algae as feedstock. The single chamber fuel cell design tested the power generation from two types of anode and cathode electron and proton transfer materials. The single cell design used in this is study consisted of a plastic container in a cylinder shape that housed both the anode and cathode. The anode and cathode compartment were made of stainless steel mesh which was either coated with activated carbon or covered with carbon cloth. This was done to assess the influence of both the coating materials on the performance of the fuel cell. The copper electrodes from the anode and cathode were connected outside the cell through the created openings. The design and materials used ensured that the cost of the cells built was significantly less than those with a proton exchange membrane, expensive catalyst and mediators. The results obtained indicated a greater power generation in the cells with the electrodes covered with carbon cloth, however, greater stability in the cells with the electrode coated activated carbon was observed.
Algae are naturally occurring organisms, that can be easily and cost effectively grown as substrates for various applications. This study compared the power generation from algae as substrates to synthetic substrates such as acetate and glucose. The algae substrate cell generated the higher voltage observed at 0.52V, with the acetate-fed cell having highest voltage output of 0.52V and with the glucose-fed cell having the highest voltage of 0.42V. It was observed that the algae cell was not able to produce power as constantly as the synthetic substrates. The glucose substrate had the best performing cell generating a power density of 62.4mW/m2, while the best acetate cell produced 29.3mW/m2 and the best preforming algae cell generated 5.1mW/m2. The organisms which were detected from all the tested MFC setups, through metagenomics, were dominated by Anaeromyxobacter sp, Shewanella oneidensis, Clostridium sp., Bacillus safensis/megaterium and Methanosaeta sp which are organisms which have been determined to be electroactive.
Keywords: Microbial fuel cell; Microalgae, Power Density, Voltage, Stainless Steel Mesh Electrode; Activated sludge.